1. Field of the Invention
The present invention relates to an image processing method, a program, an image processing apparatus, an image-pickup optical apparatus, and a network device.
2. Description of the Related Art
In a virtual slide system, a digital object image is obtained by a digital image-pickup optical apparatus, which is referred to as a virtual slide. In general, in the medical field, a specimen (preparation) is prepared as an object by covering a sample with an optical element, such as a cover glass, in a fixed state. The virtual slide includes a microscopic optical system, an image sensor, and an information processing unit, forms a digital image of the preparation, and stores the image data.
A doctor examines the image obtained from the image sensor, but due to random noises generated in the image sensor, such as a charge-coupled device (“CCD”), a complementary metal-oxide semiconductor (“CMOS”), and a photomultiplier tube (“PMT”) during the image acquisition, it is necessary to effectively denoise the obtained image. Japanese Patent Laid-Open No. (“JP”) 10-304361 proposes a denoising method configured to suppress a high frequency component in a transformed image by applying a discrete cosine transform to the image. JP 2007-274064 discloses a denoising method for an image at an in-focus position by obtaining images at a plurality of different positions in an optical axis direction and by processing a noise component based on the similarity between images. J. B. Sibarita, “Deconvolution Microscopy,” in “Microscopy Techniques,” Jens Rietdorf edited, U.S. Springer, 2005, p. 201-243, (“Sibarita”) proposes a method of obtaining a high resolution image by applying a frequency filter to a plurality of images at a plurality of different positions in the optical axis direction. Another technique of the prior art is Min Gu, “Principles of Three-Dimensional Imaging in Confocal Microscopes,” U.S., World Scientific, 1996 (“Gu”).
However, the method disclosed in JP 10-304361 has difficulties in denoising a low frequency region. The method disclosed in JP 2007-274064 assumes a constant noise regardless of the position in the optical axis direction or regularly distributed noises with the position in the optical axis direction, and it is therefore difficult to reduce the random noises. The approach disclosed in Sibarita attempts to recover a blurred image due to the optical system, and it does not address denoising.